Waterproof plaster board and method of producing same



Dec. s, 1925. 1,564,625

C. P. RITCHIE WATERPROOF PLASTER BOARD AND METHOD OF PRODUCING SAME Filed Jan. 9, 1924 meme Der. s, 192s.

CARLETON 1". RITCI-IIE, OF LOS ANGELES,

CALIFORNIA, ASSIGNOR TO lKLINCH-LATH CORPORATION, OF LOS ANGELES, CALIFORNIA, A CORPORATION OF CALIFORNIA.

'IITAlERIzROOl` PLASTER BOARD AND METHOD OF PRODUCING SAME.

Application mea ranuary 9, 1924.. serial No, 685,199.

`To all 'whom z't may concern.

Be it known that I, CARLETON P. RITCHIE, a citizen of the United States, residing'at Los Angeles, in the county of Los Angeles, State of California, have invented a new -and useful Waterproof Plaster Board and Method of Producing Same, of which the following is a specification. E

My invention relates to plaster board such as is used in building construction. Plaster board is commonly produced by uniting one or more sheets of paper with an intermediate layer of plaster, the plaster adhering to the paper and forming a thin board which may be used for exterlor or interior purposes. In some cases the plaster board is nailed to suitable studding an'd is painted to form partitions and interior surfaces, being then known as wall board. In other cases it is used as a base for stucco on the exterior of buildings or as a base for plaster or stucco on the interior of buildings. My invention is applicable to all of these purposes.

Many inventors have attempted to produce a plaster board which is more or less impervious to moisture by using one or more layers of waterproof paper. This waterproof paper is made by impregnating an ordinary paper with tar or asphaltum. It is rather diiicult to produce a reliable plaster board in which waterproof paper 1s used on account of the fact that the waterproof paper, being water resistant, does not readily a sorb the wet plaster and the bond between the paper and the plaster after setting is not very ood. Where unsized or untreated paper 1s used, the paper being water4 absorbent` readily allows the plaster to penetrate into the mesh of the paper and a remarkably permanent and solid bond is produced between the plaster and the paper.

It is 'an object of In invention to provide a plaster board whic when completed, is quite waterproof nd in which the bond between the waterpftoof paper and the plaster is very good.

Further ob"ects and advantages will be made evident ereinafter.

Referring to the drawings which are for illustrative purposes only,

Fig. 1 is an elevation of the pa er used, the paper being torn into three ayers to show the construction thereof.

Fig. 2 is a section on a very much enp impregnated largied scale through a portion of the paper use Fig. 3 is a section on a full sized scale of the completed plaster board.

' In the use of my invention I employ a paper consisting of three layers 11,12 and 13. The layers 11 and 13 are of ordinary pa er, such as is used in the manufacture of oxes and for other purposes. This paper may be sized or not, but in any event it should be slightly water absorbent and preferably somewhat loose in texture. Incorporated in the paper between the layers 11 and 13 4is a layer 12 which has been thoroughly impregnated with tar or asphaltum. Paper of this general character can be purchased on the market and its method of manufacture is well understood.

In the production of my preferred form of plaster board, I employ this paper in the ordinary manner running it over rollers and incorporating a layer of wet plaster 14 between two layers 15 4and 16 of the above described paper. The layers 11 and 13, being water a sorbent, readily form a very complete bond with the plaster 14 as (it sets, either side of the paper being placed next to the plaster. In the ordinary practice of my invention I may use only one sheet of paper 15, the other sheet 16 being the ordinary paper. Or I may use paper of the general form shown in Fig. 2 for both the layers 15 and 16. After forming the board, it is allowed to set, and is thoroughl hardened. It is then laced in a kiln, in w ich it is heated to a su cient tem.- perature to melt the impregnating material in the layer 12. This material as it melts spreads to the la ers 11 and 13, impregnating the same an thoroughly waterproofing the entire surface of the board.

I claim as my invention:

1. A method of' producing a waterproof plaster board which comprises: preparing a palper partially saturated with a water roof su stance, one surface of said paper eing initially free from said substance; preparing a plaster board in which said untreated surface is in contact with the plaster which adheres readily thereto; and thereafter treating said plaster board -to cause said waterproof substance to Spread through said paper.

2. A method of producing a waterproof plaster board which comprises: preparing a paper partially saturated with a waterproof substance, one surface of said paper eing initially free from said substance; preparn a plaster board in which said untreate surface is in contact with the plaster Whichadheres readily thereto; and thereafter heating said plaster board to a suiiicient temperature to cause said Waterproof substance to spread through said aper.

3. A methody of roducing -a Waterproof plaster board whic comprises: unitm a paper having a Water absorbing sur ace and a waterproof inner core with a layer of plaster, in such a manner that the plaster permeates and unites with the paper adjacent to said Water absorbing surface; and thereafter heating the plaster board to cause 20 the waterproofing material in said waterproof inner core to spread into the paper adjacent to said water absorbing surface.

4. A method of producing a `Waterproof plaster board which comprises: formmg a plaster board with a aper which is partially impregnated Wit a waterproof substance; and thereafter treatin the board to spread said sbstance throug said paper.

5. A method of roducing a Waterproof plaster board whic comprises: forming a plaster board withxfa paper which is partially impregnated wv'it a Waterproof su'bstance; and thereafter heating said board to a temperature suicient to melt said Waterproof substance and to spread said substance through said paper.

In testimony whereof, I have hereunto set my hand at Los Angeles, California, this 3rd day of Januar 1924.

CAR ETON P. RITCHIE. 

